Electrodeposition of nickel



Patented Oct. 3, 1961 nice 3,002,902 ELECTRODEPOSITION F NICKEL Donald Gardner Foulke, Watchung, Otto Kardos, Red Bank, and Herman K0retzky,'Belleville, N.J., assignors to Hanson-Van Winkle-Munning Company, a corporation of New Jersey No Drawing. Filed Sept. 26, 1958, Ser. No. 763,45

; Claims. (Cl. 204-49) This invention relates to electroplating and, more particularly, to electrodepositing nickel from an aqueous acidic nickel plating bath. The invention is based on the discovery that the bisulfite addition products of acetylenic compounds, when incorporated in a nickel electroplating bath, are remarkably effective for promoting the formation of very bright and ductile electrodeposits of nickel over a wide current density range and, more over, that certain of these bisulfite adducts are also capable of exerting a pronounced leveling eflect on the electroplate formed during the plating operation.

Theoretically, there are at least two possible bisulfite addition products which may be formed from a given acetylenic compound. Disregarding the numerous optical and geometrical enantiomorphs which chemical theory predicts may be formed, the addition of a bisulfite to an acetylenic bond proceeds in two successive stages, the first of which results in the formation of an initial bisulfite addition product which, in turn, reacts in the second stage to produce a second bisulfite adduct. The extent of the reaction is dependent upon and therefore controlled by the molar proportions of bisulfite present in the reaction mixture. Although the proof of structure of each of the two adducts is far from conclusive, the initial bisulfite addition product of an acetylenic compound appears to be a conjugated 0a,}3-UI1S3tl1l'8tfid sulfonic acid (or sulfonate) which is capable of undergoing further addition, in the presence of excess bisulfite, to form the second adduct. The apparent structure of this second bisulfite addition product is that of a saturated disulfonic acid (or disulfonate), in which the sulfonic acid (or sulfonate) groups are vicinal.

Following an exhaustive investigation into the chemistry of bisulfite addition to acetylenic bonds, it has been discovered that the bisulfite addition products prepared by reacting a,a-disubstituted acetylenic compounds with N times an equimolar quantity of a compound capable of forming a chain-carrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compound, are unusually efiective for promoting the formation of bright and even brilliant electrodepo'sits of nickel over very wide current density ranges when a minute quantity of the bisulfite adduct is incorporated in an aqueous acidic nickel plating bath. In addition to their brightening capacity, these bisulfite addition products have also been found to exert a pronounced leveling effect during the formation of the electrodeposit.

As a general rule, the bisulfite addition products of any u,u-disubstituted acetylenic compound having a functional group on each of the carbon atoms adjacent to the acetylenic bond (or to one of the acetylenic bonds it the compound is a polyene) may be selected for inclusion in nickel plating baths. It is of course necessary that the particular a,a-disubstituted acetylenic compound used to prepare the bisulfite adduct contain at least one m,ot'-diSllbStit11t6d acetylenic bond which is neither sterically nor electronically hindered from undergoing reaction with a chain-carrying sulfite radical, and that the bisulfite adduct be capable of being dissolved in acid without undergoing decomposition.

Only very small quantities of these bisulfite addition products are required in the plating bath, for c0ncentrations as low as 0.1 millimole per liter have been found to be effective. In many cases, however, at least 1 millimole per liter of the bisulfite addition products should be employed to secure the full benefit of their presence in the bath. There appears to be no critical upper limit on the concentration of these bisulfite addition products save solubility, but there is generally no advantage in employing more than 100 millimoles per liter, and in most plating baths substantially the full benefit of its presence is achievedwith 2O millirnoles per liter, or even less.

Accordingly, the invention provides an improved process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic nickel plating solution of at least one nickel salt in which there is dissolved from about 0.1.to about 100 millirnoles per liter of the bisulfite addition product of an oz,oc'-disubstituted acetylenic compound and N times an equivalent weight of a compound capable of forming a chaincarrying sulfite radical, where N is equal to the number of acetylenic bonds per molecule of the acetylenic compounds. The common structural feature of the oc,oc'-disubstituted acetylenic compounds used in preparing these bisulfite addition products is the presence of a functional group (R, and R on each of the carbon atoms vicinal (or alpha) to an acetylenic bond, as represented by the following structural configuration:

RF LOE Each of these functional groups (R,, and R or substituents is selected from the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups having the structure O[OHg( DH-O],,H in which R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxy methyl, ethenyl, and glycidyl, and n is an integer from 1 to 20.

The bisulfite addition products are conveniently prepared by refluxing an aqueous solution containing both the acetylenic compound and an alkali metal bisulfite (or sulfite) until most of the bisulfite (or sulfite) ions have been consumed. The rate at which bisulfite ion is consumed in the reaction mixture is accelerated by passing gaseous oxygen through the mixture or by adding a trace amount of a free radical initiator (i.e., benzoyl peroxide) to the reactants; the rate is sharply diminished, on the other hand, by adding trace amounts of free radical inhibitors, such as hydroquinone and similar antioxidants, to the reaction mixture. From these observations, it may be concluded that bisulfite addition to an acetylenic bond occurs primarily by a radical chain process, in which the chain-carrying steps may be positulated as proceeding via the following reaction sequence:

The exact nature of the chain-carrying sulfite radical is not actually known, since a similar chain involving HSO can be Written. Both species -9 and H80 have been proposed for the autoxidation of bi sulfite and sulfite ions by oxygen, and hence either may be the transitory intermediate which adds tothe acetylenic bond. No matter what the transitory intermediate radical, however, any compound which is capable of forming a chain-carrying sulfite radical may be used to form the bisulfite adduct. The term compound capable of forming a chain-carrying sulfite radical denotes the alkali metal or metal bisulfites, sulfites, and metabisulfites, as well as sulfurous acid or gaseous sulfur dioxide. All of these compounds may be used to form bisulfite adducts of :,0t-diSl1bStiil1t6d acetylenic compounds which, in turn, may be used in nickel plating baths in accordance with this invention.

, Even though all of the available evidence indicates that bisulfite addition to the acetylenic bond of an a,a'- disubstituted acetylenic compoundis radical in nature, and that consequently the predominant product form'ed is the corresponding conjugated sulfonic acid ('or sulfonate), the possibility that bisulfite or sulfite ions form charge-transfer complexes with a'cetylerli'c bonds, or that bisulfite or sulfite ions undergo ionic addition to an acetylenic bond, cannot be completely dismissed.

After the bisulfite adduct has been prepared, the reaction mixture may be added directly (or decolorized and then added directly) to the nickel plating bath or, alternatively, the bisulfite addition product 'may be pre- 'cipitated or crystallized from the reaction mixture and then added to the plating bath, the same plating results being obtained in either case. Although the bisulfite addition products may be used in concentrations as high as 100 millimoles per liter, or even more, there is no particular advantage to be gained from the higher concentrations, and they are preferably used in the range of concentrations from about 0.1 to about 20, or even in the relatively narrow range from 1 to 20 millimoles per liter.

While the bisulfite addition products of any a,m'-disubstituted acetylenic compound can be employed with success in the process of the invention for producing bright nickel deposits, particularly outstanding results have been obtained by using in the plating bath bisulfite addition products of those a,u-disubstituted acetylenic compounds which contain only a single acetylenic bond, particularly the bisulfite adducts of 1,4-disubstituted-2- butynes. Prepared in the usual manner by reacting a particular l,4-disubstituted-2-butyne with an equimolar quantity of a compound capable of forming a chaincarrying sulfite radical (preferably an alkali metal bisulfite), the bisulfite addition products of 1,4-disubstituted-2-butynes, when incorporated in a nickel plating bath, have been found to exert a pronounced leveling effect during electrodeposition on the basis metal as well as to induce the formation of brilliant nickel deposits over a wide current density range.

Among the most satisfactory of these butyne-bisulfite addition products, all of which possess both brightening and leveling properties, are those which are prepared from 1,4-disubstituted-2-butynes having a structure represented by the formula in which the functional groups R, and R are either hydroxy, alkoxy, formoxy, alkanoxy (i.e., acetoxy), halogen, or polyoxy groups having the structure RD -0'[CHz()H-0],;H

in which R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20. If both of the functional groups R and R of the acetylenic compound are the same (R =R then the acetylenic compound is symmetrical, but if both are dissimilar, then the alkyne is unsymmetrical. Bisulfite addition to a symmetrically substituted Z-butyne generally yields the corresponding 1,4-disubstituted-2-butene-2-sulfonic acid (or sulfonate), whereas bisulfite addition to an unsymmetrically substituted Z-butyne generally yields a mixture of isomeric Z-butene-Q-sulfonic acids or their salts. Table I lists a number of examples of various 1,4-disubstituted-2-butynes, both symmetrical and unsymmetrical, which have been used to prepare bisulfite addition products which, in turn, have been successfully employed in embodiments of this invention.

TABLE I 1,4-disubstituted-2-butynes R CH CECCH Rb Compound R, R

2-Butyne-1,4-diol O H -O H 4-Meth0xy-2-buty11-1-ol t 0 H O 0 H 4-Forrnoxy-2-butyn-1-ol 0 H O (I? H 4-A0et0xy-2-outyn-1-ol -0 H 0 (l? C H 3 butyne O OH; Ol 1,4-Diethoxy-2-butyne -O C I-I O C H 1,4-Dichloro-2-butyne -Cl -Ol 1,4-Dibr0mo-2-butyne Br Br 1,4-Diacetoxy-2-butyne 0 E) 0 H3 -O (6 CH:

4 (,5 hydronyethoxy) 2- butync OCH1CHZOH -OGH;CH2OH 4 (8 hydroxy 7 chloropropoxy)-2-butyne O CH CH-OH -O CHgCH-OH All of the available evidence indicates that the reaction of a l,4-disubstituted-Z-butyne with an equimolar quantity of a compound capable of forming or generating a chain-carrying sulfite radical results in the formation of a conjugated sulfonic acid or its salt as the predominant product, which may be represented by the formula in which the cation substituent M is either hydrogen, alkal-i meals, ammonium, magnesium, or nickel, and R and R are functional groups which have been previously defined. Whether the free sulfonic acid is formed (Ni-hydrogen) or whether its salt is obtained (M=Na. K, Li, NIL, Mg, or Ni) depends upon the compound used to generate the chain-carrying sulfite radical. Thus, if an alkali metal, ammonium, magnesium, or nickel bisulfite or sulfite is used, the corresponding conjugated sulfonate will be formed, but if 'sulturous acid or sulfur dioxide are employed, then the bi-sulfite adduct will be the free sulfonic acid.

In aqueous acidic nickel plating solutions, both the free sulfonic acid and its alkali metal, ammonium, magnesium, and nickel salts dissolve to form the anion of 1,4-disubstituted-2=butene-2-sul'fonic acid (I), which is represented by the formula in which the functional groups R and R are the same as before. However, when an unsymmetrical butyne (R -R is used to prepare the bisulfite addition product. the adduct is a mixture which contains, in'addition to (1'), an isomeric 1,4 disubstituted 2'- butene-Z-s'ulfonic acid (II) the anionof'Which-is shownbelowt n..c rn-o=oHo'H2 nb v fioth of these isomeric 1,4-disubstituted-2-hutene-2-sulfonic acids are the full equivalent of each other when used in nickel plating baths in accordance with the invention. The reaction mixture containing both, prepared'by reacting an unsymmetrically substituted Z-butyne with an alkali metal bisulfite, may be incorporated in nickel plating solutions without first fractionating each isomer. If the individual isomers are desired, however, then they may be separated 'by chromatographic adsorption techniques.

The predominant product formed when a symmetrically substituted 2-butyne is reacted with an equimolar quantity of an alkali metal bisulfite or sulfite is the corresponding Z-butene-Z-sulfonate. Of the many such compounds tested in nickel plating baths in accordance with the invention, particularly satisfactory results have been obtained by using the 1,4-dihydroxy-, dimethoxy-, diacetoxy-, di-(B-hydroxyethoxy)-, and di-(fl-hydroxy-wchloropropoxy)-2-butene-2-sulfonates or the corresponding free sulfonic acids in nickel plating baths.

The following examples are illustrative of the efiectiveness with which the bisulfite addition product of various l,4-disubstituted-2-butynes may be used in accordance with this invention. In each of these examples, a Watts nickel plating bath having the following basic composition was used:

Grams per liter Nickel sulfate, NiSO -7H O 300 Nickel chloride, NiCl -6H O 45 Boric acid, H BO 41.25

After adjusting the pH of the bath to 3.1 with sulfuric acid and adding varying quantities of the bisulfite addition product, an electrodeposit of nickel was formed on either a stainless steel panel or on a steel panel having roughness value (root mean square value in microinches) of 20, or on both panels, using a bath temperature of 60 C., vigorous air agitation, and an average current density of 60 amperes per square foot (unless otherwise stated). The average thickness of each electrodeposit was 0.025 mm. (0.001 inch).

EXAMPLE I The bisulfite addition product of 2-butyne-1,4-diol was prepared by refluxing equimolar proportions of Z-butyne- 1,4-diol (in the form of a 36 percent aqueous solution) and sodium bisulfite. After refluxing the reaction mixture for about 7 /2 hours, it was diluted with water, treated with activated carbon and filtered, yielding a very light yellow solution. Titration of an aliquot of the filtrate with standard iodine-potassium iodide reagent, using starch as an indicator, showed that only 2.6 mole percent of the original sodium bisulfite had remained unreacted. From both the infrared spectrum and the chemical properties of the bisulfite addition product, it was adduced that the predominant product formed during the reaction was sodium 1,4-dihydroxy-2-butene-2-sulfonate. The bisulfite addition product could be used in nickel plating baths without further purification, or it could be precipitated or crystallized from solution and then redissolved in the plating bath, the plating results being the same in either case.

The resulting bisulfite addition, when incorporated in i a nickel plating 'bath in concentrations of from 1.1 to 4.4 millimoles per liter, gave a high degree of leveling and a very Wide bright plating range of current densities. Moreover, the electroplates formed from baths containing the bisulfite adduct have notably great ductility and a remarkably low internal stress.

d was filtered, dried in vacuo, and used in the plating bath without further purification.

Using a bath temperature of 50 C. at a pH of 3.1 with vigorous air agitation, a brilliant nickel electrodeposit was formed over a very wide range of current densities on a polished steel panel from a Watts nickel plating bath containing 300 grams per liter of nickel sulfate, 45 grams per liter of nickel chloride, 41.25 grams per liter of boric acid, and 8.8 millimoles per liter of the bisulfite addition product of equimolar quantities of 4-methoxy-2- butyn-l-ol and potassium bisulfite, the preparation of which is described above. The difierence in roughness values of electroplate and the unplated polished steel panel was 52 percent, indicating that the bisulfite addition product exerted a pronounced leveling effect on the bath during the plating operation. Decreasing the concentration'o-f the bisulfite adduct in the bath to 4.4 and 2.2 Inillimoles per liter, respectively, resulted in a slight but proportionate decrease in the brightness and smoothness of the electroplate.

EXAMPLE III Excellent results are also obtained when the electroplate is formed from a plating bath containing the bisulfite addition products of a 1,4-dihalo-2-butyne. A brilliant nickel electrodeposit was formed on a polished steel panel in an open vessel, using a plating bath and plating conditions similar to those described in Example I, with the sole exception that concentrations varying from 2.2 to 6.6 millimoles per liter of the bisulfite addition product of equimolar proportions of 1,4-dichloro-2-butyne and sodiumbisulfite were used in the plating bath in place of the bisulfite adduct of 2-butyne-l,4-diol. The difference in roughness values of the electroplate and the unplated polished steel panel was 25 percent, indicating that the bisulfite addition product exerted a pronounced leveling effeet on the bath during the plating operation. Moreover, both the adhesion of the deposit and the foil ductility of the plated panel were excellent when an unbent stainless steel panel was used in place of the polished steel panel.

EXAMPLE IV To a dilute aqueous solution of 1,4-di-(B-hydroxyethoxy)-2-butyne was added an equimolar quantity of sodium bisulfite and the reaction mixture refluxed for about 7 hours. After cooling, the solution was further diluted with water, treated with activated carbon, and filtered under suction, yielding an almost colorless filtrate. The predominant product formed during the reaction was sodium 1,4-di-(fi-hydroxyethoxy)-2-butene-2-sulfonate.

An electrodeposit of nickel was formed in an open vessel on panels of steel and polished stainless steel, using a basic Watts bath having substantially the same composition (in nickel sulfate, nickel chloride, and boric acid) described previously. The deposit formed at a bath temperature of C. and at a pH of 3.1 to 3.5 was matte and slightly stressed. Upon adding 2.2 millimoles per liter of the bisulfite adduct of 1,4-di-(B-hydroxyethoxy)-2- butyne to the bath, a bright to brilliant electrodeposit was formed under the same plating conditions. Both the adhesion of the deposit to the stainless steel and the ductility of the foil were excellent. Increasing the bath concentration of the bisulfite adduct to 4.4 millimoles per liter resulted in a slight increase in brilliance of the electroplate and a marked increase in the leveling eflect.

EXAMPLE: V

The bisulfite addition product of 1,4-di-(p-hydroxychloropropoxy)-2-butyne, which is the reaction product of 2-butyne-1,4-diol and epichlorohydrin, was prepared by adding an equimolar proportion of 1,4-di-(fi-hydroxychloropropoxy) -2-butyne to an aqueous solution of sodium bisulfite and refluxing the mixture for several hours. After cooling, the solution was diluted, decolorized with activated carbon, and filtered. Methanol was added to the filtrate, with vigorous stirring, to precipitate the bisulfite 7 addition product. After filtration, the precipitate was dried in vacuo and used without further purification.

A brilliant and ductile electrodeposit of nickel was formed on a polished steel panel, using a plating bath and plating conditions similar to those described in Example I with the sole exception that 2.2 millimoles per liter of the bisulfite addition product of 1,4-di-(fl-hydroxy- 'y-chloropropoxy)-2-butyne, the preparation of which is described above, were used in the bath in place of the bisulfite adduct of 2-butyne-l,4-diol. Measurement of the roughness values (root means square value in microinches) of both the unplated and plated panel, using a Brush Surface Analyzer, showed that the roughness of the plated panel had decreased by over 56 percent from that of the unplated panel, indicating that the use of the bisulfite addition product in the bath is accompanied by leveling during the plating operation.

EXAMPLE VI Equimolar proportions of 1,4-diacetoxy-2-butyne and sodium bisulfite were dissolved in water and the resultant solution refluxed for about 5 hours. The reaction mixture was diluted with water, rlecolorized with activated carbon, filtered under suction, and the filtrate used in a plating bath without further purification.

When 2.2 millimoles per liter of this bisulfite addition product were added to a Watts nickel plating bath having substantially the same composition (in nickel sulfate, nickel chloride, and boric acid) of Example I, the nickel deposit formed on a Hull cell steel test panel at 60 C. and at a pH of 3.1 to 3.5 was uniformly bright over almost the entire current density range. Similarly, when a panel of stainless steel was plated under identical conditions, both the adhesion of the electrodeposit to the basis metal and the ductility of the plated foil were excellent.

Although the basis or reaction mechanism by which the bisulfite addition products of a, x'-disubstituted acetylenic compounds (particularly the adducts of 1,4-disubstituted- Z-butynes) function in a nickel plating bath is not completely understood, it is evident from the foregoing examples that incorporating these bisulfite adducts in an acidic nickel plating bath promotes the formation of bright to brilliant ductile electrodeposits over a wide current density range and allows the plating operation to be carried out at high temperature and a low pH without danger of marring the appearance of the electroplate.

The foregoing examples show the advantages attained when the bisulfite addition products of a,a'-disubstituted acetylenic compounds are used in a Watts nickel plating bath, which is prepared by dissolving nickel sulfate and nickel chloride in water and containing also boric acid. Similar advantages also are attained when these bisulfite adducts are dissolved in other types of aqueous acidic nickel electroplating baths. For example, their use is beneficial in straight nickel sulfate baths, in straight nickel chloride baths, and in such other aqueous nickel electroplating baths as those based on using nickel formate, nickel sulfamate, or nickel fluoborate as the nickel salt which is dissolved in the aqueous acidic solvent. The invention therefore contemplates the use of the bisulfite addition products of a,a'-disubstituted acetylenic compounds in any aqueous acidic nickel electroplating bath.

We claim:

1. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 100 millimoles per liter of the bisulfite addition product of an 0t,0c'-diSllbstituted acetylenic compound and N times an equivalent weight of a compound capable of forming a chain-carrying sulfite radical selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and equal to the number of acetylenic bonds in the acetylenic compound, said bisulfite addition product containing the structmral co'nfiguration R.i(:3OH=C(:3Rb

in which each of R and R are substituents of the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups having the structure O-[OH;( ]I-IO]nH in which R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, n is an integer from 1 to 20 and M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.

2. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 20 rnillimoles per liter of a compound represented by the formula in which each of R and R are substituents selected from the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups having the structure R0 O-[CH ]H-O]n--H in which R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20, and M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.

3. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 20 millimoles per liter of a compound represented by the formula in which R is a substituent selected from the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups having the structure R0 O-[CHg( JH-O] H in which R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 1 to 20, and M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.

4. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 20 millimoles per liter of a compound represented by the formula R,0H2-CH=CCH2X souvr in which X is a halogen, and R is a substituent selected from the group consisting of hydroxy, alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups having the structure R0 o[cH2 3H-0],,H

in which R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, and n is an integer from 9 1 to 20, and M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.

The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.1 to about 20 millimoles per liter of a compound represented by the formula in which R is a substituent selected from the group consisting of hydrogen, methyl, chloromethyl, hydroxymethyl, ethenyl, and glycidyl, n is an integer from 1 to 20, and R is a substituent selected from the group consisting of hydroxy, alkoxy, alkanoxy, halogen, and polyoxy groups having the structure R0 ocH2('JH o .,-H

and M is a cation substi-tuent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.

6. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 1 to about 20 millimoles per liter of the bisulfite addition product of equivalent weights of 2-butyne-1,4-diol and a compound capable of forming a charm-carrying sulfite radical selected from the group consisting of sulfiurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product having a structure represented by the formula in which M is a cation substituent selected firom the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.

7. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 1 to about 20 millimoles per liter of the bisulfite addition product of equivalent weights of 1,4-di-(B-hydroxyethoxy)-2-butyne and a compound capable of forming a chain-carrying sulfite radical selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product having a structure represented by the formula in which M is a cation substituent selected firom the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.

8. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aque ous acidic solution of at least one nickel salt in which there is dissolved from about 1 to about 20 millimoles per liter of the bisulfite addition product of equivalent weights of 1,4-di-(ti-hydroxy-' -chloropropoxy)-2-butyne and a compound capable of forming a chain-carrying sulfite radical selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product having a structure represented by the formula in which M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.

9. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 1 to about 20 millimoles per liter of the bisulfite addition product of equivalent weights of l,4-dimethoxy-2-butyne and a compound capable of forming a chain-carrying sulfite radical selected from the group consisting of sulfurous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product having a structure represented by the formula H3COCH2 CH=CCHTOCHB soot in which M is a cation substituent selected firom the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.

10. The process for producing bright nickel deposits which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 1 to about 20 millimoles per liter of the bisulfite addition product of equivalent weights of 1,4-diacetoxy-2-butyne and a compound capable of forming a chain-carrying sulfite radical selected from the group consisting of sulfur-ous acid, sulfur dioxide, and the alkali metal and metal bisulfites, sulfites, and metabisulfites, said bisulfite addition product having a structure represented by the formula in which M is a cation substituent selected from the group consisting of hydrogen, alkali metals, ammonium, magnesium, and nickel.

References Cited in the file of this patent UNITED STATES PATENTS 2,427,280 Hoifman Sept. 9, 1947 2,571,286 Otto et al Oct. 16, 1951 2,667,507 Jones et a1 Ian. 26, 1954 2,671,800 Copenhaver Mar. 9, 1954 2,712,522 Kardos et =al. July 5, 1955 2,800,440 Brown July 23, 1957 FOREIGN PATENTS 634,394 Great Britain Mar. 22, 1950 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 3,002,902

October 3 1961 Donald Gardner Foulke et a1.

It is h'ereby certified that error appears in the above numbered patoorrected below.

ent requiring correction and 'that the said Letters Patent should read'as Column 1, line 62, for "polyene" read polyne column 2, lines 21 and 22, for "compounds" read compound line 56, for "positulated" read postulated column 4, line 49, for "meals" read metals line 52 for read bisulfite "M-hydrogen" read M=hydrogen line 58 for "bi-sulfite" Signed and sealed this 3rd day of April 1962..

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer DAVID L. LADD Commissioner of Patents 

1. THE PROCESS FOR PRODUCING BRIGHT NICKEL DEPOSITS WHICH COMPRISES ELECTRODEPOSITING NICKEL FROM AN AQUEOUS ACIDIC SOLUTION OF AT LEAST ONE NICKEL SALT IN WHICH THERE IS DISSOLVED FROM ABOUT 0.1 TO ABOUT 100 MILLIMOLES PER LITER OF THE BISULFITE ADDITION PRODUCT OF AN A,A''-DISUBSTITUTED ACETYLENIC COMPOUND AND N TIMES AND EQUIVALENT WEIGHT OF A COMPOUND CAPABLE OF FORMING A CHAIN-CARRYING SULFITE RADICAL SELECTED FROM THE GROUP CONSISTING OF SULFUROUS ACID, SULFUR DIOXIDE, AND THE ALKALI METAL AND METAL BISULFITES, SULFITES, AND METABISULFITES, WHERE N IS EQUAL TO THE NUMBER OF ACETYLENIC BONDS IN THE ACETYLENIC COMPOUND SAID BISULFITE ADDITON PRODUCT CONTAINING THE STRUCTURAL CONFIGURATION 